Hereditary benign intraepithelial dyskeratosis (HBID) is an autosomal dominant cell proliferation disorder characterized by opaque epithelial plaques on the optical conjunctiva and oral mucosa. Plaques appear at birth or in early childhood, recur throughout life, and can obstruct vision. The characteristic red eye appearance leads to many difficulties in social interactions and employment because affected individuals are often presumed to be under the influence of drugs. The gene for this disorder has been linked to chromosome 4q35, and a near-telomeric DNA duplication discovered in this region is the most likely cause of the disease. We propose to investigate the role the DNA duplication plays in HBID by performing a detailed molecular analysis of the duplicated region and candidate genes. Conjunctival tissue from normal individuals and biopsied lesion material from HBID patients will be collected for gene expression analysis. A limited number of extremely promising candidate genes will be transfected into an established cell culture system to test candidate genes on their ability form foci, which is consistent with the HBID phenotype.